Zoo staff had reportedly been monitoring Adhama’s health since late last week, after observing a change in his energy and appetite.

“Adhama spent Monday and Tuesday behind the scenes under observation and resting, but there was nothing to indicate a serious issue,” the zoo explained in a release. “After hours on Tuesday evening, keepers observed via closed-circuit video that Adhama seemed to be non-responsive, and our animal care team responded immediately. Unfortunately, the team found that he had passed away suddenly with no external signs of stress or trauma.”

WATCH: Gorilla Dancer Shows Off His Moves

Adhama and his mate Boipelo came to the Dallas Zoo in March 2017 ahead of the opening of the its Simmons Hippo Outpost the following April. Boipelo gave birth to a calf in February 2018, but the calf did not survive.

“Adhama was known for his larger-than-life personality. He was such a sweet boy, and we’ve all cherished the opportunity to get to know him and Boipelo in the past 18-plus months since the opening of our Simmons Hippo Outpost,” the zoo wrote on Facebook. “Our staff will be closely monitoring and supporting Boipelo through this difficult time.”

We are devastated to share that our beloved Adhama passed away suddenly on Tuesday evening.
The hippo keepers and our...

Preliminary findings from the veterinary team indicate Adhama died of an acute inflammation of the intestine, known as severe enteritis. Given the sudden onset and lack of significant symptoms, the team said they’re confident there’s nothing they would have done differently.

"Love is using your bae as a step stool during the lettuce toss. 💚" ~ Megan Lumpkin, hippo supervisor
We couldn't agree more.

“From the time he arrived here at the Dallas Zoo, Adhama captivated us all with his curious nature and larger-than-life personality. He was a wonderful ambassador as we opened our Simmons Hippo Outpost and reintroduced hippos to Dallas last year,” Gregg Hudson, President and CEO of the Dallas Zoo, said in a statement. “Our entire team is understandably shaken, given the suddenness of Adhama’s passing. Please keep our entire staff in your thoughts during this difficult time.”